Fasting

If there is only 1 adhaan, this is what you should stop eating at.

This is permissible.

If this is applied externally, it has no effect on your fasting.

This is not a valid reason for skipping the fast for that day. Ask permission to have a small snack, if possible. If they don’t allow you, this will not affect your mental ability and Allah will strengthen you!

Usually, the sunnah is to recite it once and this is the minimum.

One does not have to renew his intention daily. Once, in the beginning of the fasting month, is sufficient. Eating the suhoor is a sufficient intention.

The prayer is valid as a lot of the countries delay Isha more than it is supposed to be, especially in Ramadan when they fix the time of. Isha to be two hours after sunset.

If you don’t have a medical condition and you are not old and unable, you must fast everyday. Once you feel that it is going to affect you, you can break your fast only then. This must be repeated everyday and it is between you and Allah.

Wa alaikum salaam, you must break the fast.

Wa alaikum salaam, nothing in specific; just make niyyah to fast.